Antiviral drug ganciclovir is a potent inhibitor of microglial proliferation and neuroinflammation

Department of Neurology and Neurological Sciences; Immunology Interdepartmental Program; and Molecular Imaging Program at Stanford, Department of Radiology; Stanford University School of Medicine, Stanford, CA 94305Department of Neurology and Neurological Sciences; Immunology Interdepartmental Program; and Molecular Imaging Program at Stanford, Department of Radiology; Stanford University School of Medicine, Stanford, CA 94305

Department of Neurology and Neurological Sciences; Immunology Interdepartmental Program; and Molecular Imaging Program at Stanford, Department of Radiology; Stanford University School of Medicine, Stanford, CA 94305

Department of Neurology and Neurological Sciences; Immunology Interdepartmental Program; and Molecular Imaging Program at Stanford, Department of Radiology; Stanford University School of Medicine, Stanford, CA 94305

Department of Neurology and Neurological Sciences; Immunology Interdepartmental Program; and Molecular Imaging Program at Stanford, Department of Radiology; Stanford University School of Medicine, Stanford, CA 94305

Department of Neurology and Neurological Sciences; Immunology Interdepartmental Program; and Molecular Imaging Program at Stanford, Department of Radiology; Stanford University School of Medicine, Stanford, CA 94305

Department of Neurology and Neurological Sciences; Immunology Interdepartmental Program; and Molecular Imaging Program at Stanford, Department of Radiology; Stanford University School of Medicine, Stanford, CA 94305

Department of Neurology and Neurological Sciences; Immunology Interdepartmental Program; and Molecular Imaging Program at Stanford, Department of Radiology; Stanford University School of Medicine, Stanford, CA 94305

Department of Neurology and Neurological Sciences; Immunology Interdepartmental Program; and Molecular Imaging Program at Stanford, Department of Radiology; Stanford University School of Medicine, Stanford, CA 94305

Department of Neurology and Neurological Sciences; Immunology Interdepartmental Program; and Molecular Imaging Program at Stanford, Department of Radiology; Stanford University School of Medicine, Stanford, CA 94305Department of Neurology and Neurological Sciences; Immunology Interdepartmental Program; and Molecular Imaging Program at Stanford, Department of Radiology; Stanford University School of Medicine, Stanford, CA 94305

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Neuroinflammation in EAE is characterized by expansion of proliferating microglia/macrophages. 8–12-wk-old mice were immunized subcutaneously with 200 µg MOG35–55 peptide emulsified in CFA and received an i.v. injection of 400 ng pertussis toxin at the time of immunization and 48 h later. Mice were sacrificed at 21 d.p.i.; BrdU was given three consecutive days before sacrifice. (A) Cerebellar sections from 21 d.p.i. EAE mice were double immunolabeled for BrdU (red) and cell type–specific markers (green) Iba1 (microglia/macrophages), GFAP (astrocytes), and CD3 (T cells). Images were taken outside of inflammatory foci to show individual cells. Far right column shows high magnifications of the white boxed areas. The proliferating cells appear yellow (arrows) after superimposition of single color images. (B–D) Cerebellar sections from naive (day −1) and EAE (7, 14, and 21 d.p.i.) mice were double immunolabeled for BrdU+ (red) and Iba1+ (green; B). Quantification of total BrdU+ cells (C) and percentage of Iba1+BrdU+ (D) in the cerebella. Bar graphs represent the mean of three to five sections from an individual mouse and SEM (n = 5–10 mice/group). **, P < 0.01; ***, P < 0.001 by ANOVA and Dunnett’s test. The experiments were independently performed three times. Bars: (A [left] and B) 50 µm; (A, right) 10 µm.

[18F]FHBG accumulates in the CNS of EAE mice and GCV inhibits microglial proliferation in vitro. (A–C) [18F]FHBG was injected i.v. into mice with (mean clinical score = 3) or without (naive) EAE. Acquisition of PET imaging data commenced before [18F]FHBG administration and continued for 60 min. PET images were reconstructed with two-dimensional OSEM and analyzed using AMIDE. (A) Results are expressed as time activity curves depicting the signal of [18F]FHBG in whole mouse brain. (B) Mice were perfused and brains were collected at 60 min after [18F]FHBG injection. Sagittal brain sections (outlined by a dashed line) were cut using a cryostat microtome and exposed to digital autoradiography film. Bottom panel shows schematics of brain sections adapted from the mouse brain atlas (Paxinos and Franklin, 2001) that represent the approximate outline of brain structures. (C) The radioactivity in the tissues was measured with an automated gamma counter and decay-corrected to time of tracer injection. Results are expressed as the percentage of injected dose per gram of tissue (% ID/g). Bar graphs show mean + SEM (n = 3 mice/group). *, P < 0.05; **, P < 0.01 by Student’s t test. Results are from one out of two independent experiments. (D–F) BV-2 mouse microglial cells were treated with the indicated concentrations of GCV and pulsed with [3H]thymidine (D) or assessed for proliferation (E) and apoptosis (F; Annexin V) with Cellavista. Bar graphs show mean + SEM (n = 3 wells/group). *, P < 0.05; **, P < 0.01; ***, P < 0.001 by one-way ANOVA followed by Dunnett’s post-test. Each experiment was independently performed at least three times.